The present invention relates to a coating apparatus for a semiconductor process, and, in particular, to an apparatus for coating a target substrate of a thin plate, such as a semiconductor wafer or an LCD substrate, with a process liquid, such as a photo-resist liquid or a developing liquid. The semiconductor process includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having, e.g., wiring layers and electrodes to be connected to a semiconductor device on a target substrate, such as a semiconductor wafer or an LCD substrate, by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
In a process of manufacturing a semiconductor device or an LCD, coating apparatuses are utilized in various steps. A representative one of them is a coating apparatus of a photo-resist or a developing liquid, employed in a coating and developing system of the photo-resist. Such a coating apparatus should swiftly apply a process liquid to a target object, such as a semiconductor wafer or an LCD substrate, in a short period of time and efficiently perform a process with a small amount of the process liquid, without giving a shock to the target object or forming bubbles.
In light of the demand, Jpn. Pat. Appln. KOKAI Publication No. 5-55133 discloses a coating technique, which employs a spin chuck for holding a semiconductor wafer and a liquid supply nozzle arranged above the spin chuck. The supply nozzle has a number of small holes formed in the bottom of a liquid container having a rectangular shape, such that a developing liquid comes oozing through the small holes and is supplied onto the wafer.
Jpn. Pat. Appln. KOKAI Publication No. 4-124817 discloses another coating technique, which employs a supply nozzle having a delivery port of a long and narrow band shape. A process liquid is supplied to the narrow delivery port from a liquid reservoir arranged in the nozzle, and is then delivered in a long and narrow band shape from the delivery port.
Jpn. Pat. Appln. KOKAI Publication No. 7-326554 discloses still another coating technique. In this technique, a small amount of a developing liquid is supplied from a developing liquid supply nozzle, to form a liquid film on the surface of a semiconductor wafer which remains stationary right under the supply nozzle. Then, an amount of the developing liquid necessary for a predetermined liquid film thickness is supplied while moving the supply nozzle and the wafer relative to each other, to form a liquid film having the predetermined thickness on the surface of the wafer.
Where a target object, such as a semiconductor wafer or an LCD substrate, and a process liquid supply nozzle are moved relative to each other, so as to form a liquid film of a predetermined thickness on the surface of the target substrate, the supply nozzle and the substrate have to keep a certain positional relationship while they are relatively moved. For this reason, moving members require a high accuracy in running movement in order to keep their positional relationship.
Additionally, semiconductor wafers and LCD substrates have become large in recent years, thereby bringing about a difficulty in maintaining their flatness. As a result, a work table for a target substrate to be processed, having a large surface area, needs not only to keep its flatness, but also to correct the flatness of the target substrate thereon.
However, it is difficult for such a large work table to be finished with a high degree of flatness and high design accuracy. Further, a mechanism for moving a work table causes the whole apparatus to be bulky, and brings about a difficulty in providing high accuracy in planar positioning and running movement.